another problem I have seen on yanmar model 2qm15 is that the Zinc
mounting housing (Salt/raw water cooled) has the hose from the water
pump to the zinc housing mounted in a verticle orientation with the hose
from water pump to zinc housing coming from underneath the zincs house.
When replacing the original hoses I found the zinc had built up a crust
inside the hose under the zinc housing to the point where the hose was
becoming constricted by the build up, might as well replace your zincs
and check for that .

"Jeffrey P. Vasquez" wrote in message news:...

Yes, it's raw.